Peru-based UTEC (University of Engineering & Technology) and agency FCB Mayo Peru have built a massive hydroponic billboard that pulls water from the air through a series of 10 large dehumidifiers. So far, the “Air Orchard” has produced more than 2,800 heads of lettuce, which are given away to passersby. The “ad,” situated on Peru’s largest highway, also produces 96 liters of drinking water each day.

The project continues the university’s tradition of trying to solve an engineering problem creatively to attract students. In this case, the billboard is tackling the issue of pollution-free foods: Farms in that region are irrigated by local rivers that are contaminated with arsenic, lead, and cadmium. According to a release, hydroponically grown vegetables are also five times more nutritious than those grown in soil.

The university and agency originally partnered in 2013, using the dehumidifiers to pull water to be distributed in the desert region. The campaign went on to win four Gold Lions in Cannes that year. Last year, it debuted an air-purifying billboard that cleaned 100,000 cubic meters of air daily in a five-block radius.TI